Why don`t we use extremely thin oils in engines











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I understand that lower viscosity oils are way easier to pump and move around engine parts, also they form a thinner "film" on friction surfaces which could improve parts measurements precision etc.
Is it only due to increased piston rings leakage that we don't use extremely thin oils?
Are they more prone to failure in operating and high temperatures?
Are these oils easier contaminated? Maybe they are very expensive to produce???










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    up vote
    11
    down vote

    favorite












    I understand that lower viscosity oils are way easier to pump and move around engine parts, also they form a thinner "film" on friction surfaces which could improve parts measurements precision etc.
    Is it only due to increased piston rings leakage that we don't use extremely thin oils?
    Are they more prone to failure in operating and high temperatures?
    Are these oils easier contaminated? Maybe they are very expensive to produce???










    share|improve this question
























      up vote
      11
      down vote

      favorite









      up vote
      11
      down vote

      favorite











      I understand that lower viscosity oils are way easier to pump and move around engine parts, also they form a thinner "film" on friction surfaces which could improve parts measurements precision etc.
      Is it only due to increased piston rings leakage that we don't use extremely thin oils?
      Are they more prone to failure in operating and high temperatures?
      Are these oils easier contaminated? Maybe they are very expensive to produce???










      share|improve this question













      I understand that lower viscosity oils are way easier to pump and move around engine parts, also they form a thinner "film" on friction surfaces which could improve parts measurements precision etc.
      Is it only due to increased piston rings leakage that we don't use extremely thin oils?
      Are they more prone to failure in operating and high temperatures?
      Are these oils easier contaminated? Maybe they are very expensive to produce???







      oil engine-theory oil-viscosity






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      share|improve this question











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      asked Nov 20 at 14:53









      kokobill

      376120




      376120






















          3 Answers
          3






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          up vote
          16
          down vote



          accepted










          Thin oils tend to have a very poor shear stability, especially when they are hot. The function of the oil is to protect and lubricate the engine and ancillaries (i.e. turbo chargers). In certain applications it also makes up some (where an oil cooler is employed) or all (for aircooled engines such as the Beetle) of the circulated liquid cooling system.



          I'm not sure that an oil which is consistently thin and remains so once upto operating temperature exists. Most engine oils are chosen so that they will provide some protection at cold start but optimum protection when they reach their target temperature.






          share|improve this answer




























            up vote
            5
            down vote













            Tribology is a huge topic...



            But, the thinner the oil, then the more oil in terms of volume and/or the higher pressure is needed for a given tolerance between bearing and surface.



            So many things are taken into account when specifying the oil for a particular use. Operating temperature, load on the bearings, relative speed of the bearing etc etc






            share|improve this answer




























              up vote
              1
              down vote













              We are, or are starting to, for exactly the reasons you quote.



              New vehicles (VAG group for example) are starting to use 0W20 oil, with 0W16-capable engines coming soon and tests being conducted with oil as thin as 0W8.



              Source: MTZ worldwide 12/2018, "Potentials and Risks of Reducing Friction with Future Ultra-low-viscosity Engine Oils"






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                3 Answers
                3






                active

                oldest

                votes








                3 Answers
                3






                active

                oldest

                votes









                active

                oldest

                votes






                active

                oldest

                votes








                up vote
                16
                down vote



                accepted










                Thin oils tend to have a very poor shear stability, especially when they are hot. The function of the oil is to protect and lubricate the engine and ancillaries (i.e. turbo chargers). In certain applications it also makes up some (where an oil cooler is employed) or all (for aircooled engines such as the Beetle) of the circulated liquid cooling system.



                I'm not sure that an oil which is consistently thin and remains so once upto operating temperature exists. Most engine oils are chosen so that they will provide some protection at cold start but optimum protection when they reach their target temperature.






                share|improve this answer

























                  up vote
                  16
                  down vote



                  accepted










                  Thin oils tend to have a very poor shear stability, especially when they are hot. The function of the oil is to protect and lubricate the engine and ancillaries (i.e. turbo chargers). In certain applications it also makes up some (where an oil cooler is employed) or all (for aircooled engines such as the Beetle) of the circulated liquid cooling system.



                  I'm not sure that an oil which is consistently thin and remains so once upto operating temperature exists. Most engine oils are chosen so that they will provide some protection at cold start but optimum protection when they reach their target temperature.






                  share|improve this answer























                    up vote
                    16
                    down vote



                    accepted







                    up vote
                    16
                    down vote



                    accepted






                    Thin oils tend to have a very poor shear stability, especially when they are hot. The function of the oil is to protect and lubricate the engine and ancillaries (i.e. turbo chargers). In certain applications it also makes up some (where an oil cooler is employed) or all (for aircooled engines such as the Beetle) of the circulated liquid cooling system.



                    I'm not sure that an oil which is consistently thin and remains so once upto operating temperature exists. Most engine oils are chosen so that they will provide some protection at cold start but optimum protection when they reach their target temperature.






                    share|improve this answer












                    Thin oils tend to have a very poor shear stability, especially when they are hot. The function of the oil is to protect and lubricate the engine and ancillaries (i.e. turbo chargers). In certain applications it also makes up some (where an oil cooler is employed) or all (for aircooled engines such as the Beetle) of the circulated liquid cooling system.



                    I'm not sure that an oil which is consistently thin and remains so once upto operating temperature exists. Most engine oils are chosen so that they will provide some protection at cold start but optimum protection when they reach their target temperature.







                    share|improve this answer












                    share|improve this answer



                    share|improve this answer










                    answered Nov 20 at 15:00









                    Steve Matthews

                    19.4k22968




                    19.4k22968






















                        up vote
                        5
                        down vote













                        Tribology is a huge topic...



                        But, the thinner the oil, then the more oil in terms of volume and/or the higher pressure is needed for a given tolerance between bearing and surface.



                        So many things are taken into account when specifying the oil for a particular use. Operating temperature, load on the bearings, relative speed of the bearing etc etc






                        share|improve this answer

























                          up vote
                          5
                          down vote













                          Tribology is a huge topic...



                          But, the thinner the oil, then the more oil in terms of volume and/or the higher pressure is needed for a given tolerance between bearing and surface.



                          So many things are taken into account when specifying the oil for a particular use. Operating temperature, load on the bearings, relative speed of the bearing etc etc






                          share|improve this answer























                            up vote
                            5
                            down vote










                            up vote
                            5
                            down vote









                            Tribology is a huge topic...



                            But, the thinner the oil, then the more oil in terms of volume and/or the higher pressure is needed for a given tolerance between bearing and surface.



                            So many things are taken into account when specifying the oil for a particular use. Operating temperature, load on the bearings, relative speed of the bearing etc etc






                            share|improve this answer












                            Tribology is a huge topic...



                            But, the thinner the oil, then the more oil in terms of volume and/or the higher pressure is needed for a given tolerance between bearing and surface.



                            So many things are taken into account when specifying the oil for a particular use. Operating temperature, load on the bearings, relative speed of the bearing etc etc







                            share|improve this answer












                            share|improve this answer



                            share|improve this answer










                            answered Nov 20 at 14:58









                            Solar Mike

                            17.1k21030




                            17.1k21030






















                                up vote
                                1
                                down vote













                                We are, or are starting to, for exactly the reasons you quote.



                                New vehicles (VAG group for example) are starting to use 0W20 oil, with 0W16-capable engines coming soon and tests being conducted with oil as thin as 0W8.



                                Source: MTZ worldwide 12/2018, "Potentials and Risks of Reducing Friction with Future Ultra-low-viscosity Engine Oils"






                                share|improve this answer



























                                  up vote
                                  1
                                  down vote













                                  We are, or are starting to, for exactly the reasons you quote.



                                  New vehicles (VAG group for example) are starting to use 0W20 oil, with 0W16-capable engines coming soon and tests being conducted with oil as thin as 0W8.



                                  Source: MTZ worldwide 12/2018, "Potentials and Risks of Reducing Friction with Future Ultra-low-viscosity Engine Oils"






                                  share|improve this answer

























                                    up vote
                                    1
                                    down vote










                                    up vote
                                    1
                                    down vote









                                    We are, or are starting to, for exactly the reasons you quote.



                                    New vehicles (VAG group for example) are starting to use 0W20 oil, with 0W16-capable engines coming soon and tests being conducted with oil as thin as 0W8.



                                    Source: MTZ worldwide 12/2018, "Potentials and Risks of Reducing Friction with Future Ultra-low-viscosity Engine Oils"






                                    share|improve this answer














                                    We are, or are starting to, for exactly the reasons you quote.



                                    New vehicles (VAG group for example) are starting to use 0W20 oil, with 0W16-capable engines coming soon and tests being conducted with oil as thin as 0W8.



                                    Source: MTZ worldwide 12/2018, "Potentials and Risks of Reducing Friction with Future Ultra-low-viscosity Engine Oils"







                                    share|improve this answer














                                    share|improve this answer



                                    share|improve this answer








                                    edited Nov 22 at 6:12

























                                    answered Nov 20 at 21:42









                                    Tobias Weiß

                                    1112




                                    1112






























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